In many imaging systems, such as imagesetters or platesetters, a movable optical carriage is used to displace a laser system or other imaging source in a slow scan direction along a stationary or moving, curved or planar, media support surface (e.g., external drum, internal drum, flatbed, or other support surface). The imaging source exposes a supply of recording media supported on, and held against, the media support surface. Generally, the imaging source includes an optical system for scanning one or more laser or other radiation beams, each modulated by a digital information signal, over the recording media to record an image onto the recording media.
For example, in an external drum imaging system, the information signal is recorded onto a supply of recording media mounted about the external drum by displacing the imaging source relative to the external drum. This may be accomplished in a number of ways, including a rotation of the external drum in combination with a lateral translation of the imaging source, a rotation and translation of the external drum past a stationary imaging source, etc. Generally, for system compactness, the external drum is rotated while the imaging source is displaced in discrete steps or continuously along the length of the external drum to record data onto the recording media.
The recording media to be imaged by an imaging system is commonly supplied in web form or in discrete sheets or plates. The recording media may include a photosensitive, radiation sensitive, thermally sensitive, or other type of imageable material.
The throughput of an external drum imaging system (e.g., the number of plates/hour that can be imaged by the system) is dependent upon a multitude of factors. For example, the time required for a stationary external drum to be rotated up to the speed required for imaging (e.g., 100-1000 revolutions per minute (rpm)), or conversely, the time required to bring a rotating external drum to a stop to remove imaged recording media and then load new recording media, greatly affects the throughput of the imaging system. The throughput of the imaging system may be increased, therefore, by increasing the rotational (angular) acceleration/deceleration of the external drum. Heretofore, increased angular acceleration/deceleration of the external drum has been achieved using larger and more powerful drive motors, power supplies, braking systems, etc. Unfortunately, although quite effective, the use of such systems greatly increases the complexity, cost, size, etc., of the imaging system.